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          <h1 class="post-title" itemprop="name headline">Java注解</h1>
        

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        <p>本文讲解Java注解的知识<br>视频课程地址：<a href="https://www.imooc.com/learn/456" target="_blank" rel="noopener">https://www.imooc.com/learn/456</a></p>
<a id="more"></a>


<h2 id="Java注解"><a href="#Java注解" class="headerlink" title="Java注解"></a>Java注解</h2><blockquote>
<p>JDK1.5+支持<br>官方概念：Java提供了一种原程序中的元素关联任何信息和任何元数据的途径和方法</p>
</blockquote>
<p><strong>Java注解的作用</strong></p>
<ol>
<li>读懂别人的代码，特别是框架相关的代码</li>
<li>让编程更加简洁，代码更加清晰</li>
<li>装X必备</li>
<li>重点是开发自定义注解</li>
<li>常用注解<br><img src="/blog/images/20191108162025452.jpg" alt="常用注解"></li>
</ol>
<h2 id="注解分类"><a href="#注解分类" class="headerlink" title="注解分类"></a>注解分类</h2><p><img src="/blog/images/20191108163251545.jpg" alt="注解分类"></p>
<h2 id="自定义注解"><a href="#自定义注解" class="headerlink" title="自定义注解"></a>自定义注解</h2><h3 id="创建自定义注解"><a href="#创建自定义注解" class="headerlink" title="创建自定义注解"></a>创建自定义注解</h3><figure class="highlight less"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br><span class="line">7</span><br><span class="line">8</span><br><span class="line">9</span><br><span class="line">10</span><br><span class="line">11</span><br></pre></td><td class="code"><pre><span class="line"><span class="variable">@Target</span>(&#123;ElementType.METHOD,ElementType.TYPE&#125;)</span><br><span class="line"><span class="variable">@Retention</span>(RetentionPolicy.RUNTIME)</span><br><span class="line"><span class="variable">@Inherited</span></span><br><span class="line"><span class="variable">@Documented</span></span><br><span class="line">public <span class="variable">@interface</span> Description &#123;</span><br><span class="line">    <span class="comment">//如果只有一个成员，成员名只能是value，即形式如下：</span></span><br><span class="line">	<span class="comment">//String value();</span></span><br><span class="line">	<span class="selector-tag">String</span> <span class="selector-tag">desc</span>();</span><br><span class="line">	<span class="selector-tag">String</span> <span class="selector-tag">author</span>();</span><br><span class="line">	<span class="selector-tag">int</span> <span class="selector-tag">age</span>() <span class="selector-tag">default</span> <span class="selector-tag">18</span>;</span><br><span class="line">&#125;</span><br></pre></td></tr></table></figure>

<p><img src="/blog/images/20191108164456069.jpg" alt="自定义注解的语法"></p>
<h3 id="使用自定义注解"><a href="#使用自定义注解" class="headerlink" title="使用自定义注解"></a>使用自定义注解</h3><figure class="highlight kotlin"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br><span class="line">7</span><br></pre></td><td class="code"><pre><span class="line"><span class="keyword">public</span> <span class="class"><span class="keyword">class</span> <span class="title">Person</span> </span>&#123;</span><br><span class="line"></span><br><span class="line">	<span class="meta">@Description(desc=<span class="meta-string">"red"</span>,author=<span class="meta-string">"liu"</span>, age=18)</span></span><br><span class="line">	<span class="keyword">private</span> String eyeColor()&#123;</span><br><span class="line">		<span class="keyword">return</span> <span class="string">"red"</span>;</span><br><span class="line">	&#125;</span><br><span class="line">&#125;</span><br></pre></td></tr></table></figure>

<p><img src="/blog/images/20191108165035563.jpg" alt="使用自定义注解"></p>
<h3 id="解析注解"><a href="#解析注解" class="headerlink" title="解析注解"></a>解析注解</h3><blockquote>
<p>解析注解： 通过反射获取类、函数或成员上的<strong>运行时注解</strong>信息，从而实现动态控制程序运行的逻辑</p>
</blockquote>
<figure class="highlight gradle"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br><span class="line">7</span><br><span class="line">8</span><br><span class="line">9</span><br><span class="line">10</span><br><span class="line">11</span><br><span class="line">12</span><br><span class="line">13</span><br><span class="line">14</span><br><span class="line">15</span><br><span class="line">16</span><br><span class="line">17</span><br><span class="line">18</span><br><span class="line">19</span><br><span class="line">20</span><br><span class="line">21</span><br><span class="line">22</span><br><span class="line">23</span><br><span class="line">24</span><br><span class="line">25</span><br><span class="line">26</span><br><span class="line">27</span><br><span class="line">28</span><br><span class="line">29</span><br><span class="line">30</span><br><span class="line">31</span><br><span class="line">32</span><br><span class="line">33</span><br><span class="line">34</span><br><span class="line">35</span><br><span class="line">36</span><br><span class="line">37</span><br><span class="line">38</span><br><span class="line">39</span><br><span class="line">40</span><br><span class="line">41</span><br></pre></td><td class="code"><pre><span class="line"><span class="keyword">public</span> <span class="keyword">class</span> ParseAnno &#123;</span><br><span class="line"></span><br><span class="line">	<span class="keyword">public</span> <span class="keyword">static</span> <span class="keyword">void</span> main(String[] args) &#123;</span><br><span class="line">		<span class="comment">//1. 获取类的类类型</span></span><br><span class="line">		<span class="keyword">try</span> &#123;</span><br><span class="line">			<span class="keyword">Class</span> class1 = <span class="keyword">Class</span>.forName(<span class="string">"com.aiolos.anno.Person"</span>);</span><br><span class="line">			</span><br><span class="line">			<span class="comment">//2. 找到类上的注解</span></span><br><span class="line">			<span class="keyword">boolean</span> isExist = class1.isAnnotationPresent(<span class="keyword">Description</span>.<span class="keyword">class</span>);</span><br><span class="line">			<span class="keyword">if</span>(isExist)&#123;</span><br><span class="line">				<span class="comment">//3. 拿到注解实例</span></span><br><span class="line">				<span class="keyword">Description</span> <span class="keyword">description</span> = (<span class="keyword">Description</span>)class1.getAnnotation(<span class="keyword">Description</span>.<span class="keyword">class</span>);</span><br><span class="line">				System.out.<span class="keyword">println</span>(<span class="keyword">description</span>.desc());</span><br><span class="line">			&#125;</span><br><span class="line">			</span><br><span class="line">			<span class="comment">//4. 找到方法上的注解: 遍历所有方法</span></span><br><span class="line">			Method[] methods = class1.getMethods();</span><br><span class="line">			<span class="keyword">for</span>(Method m: methods)&#123;</span><br><span class="line">				<span class="keyword">boolean</span> isHave = m.isAnnotationPresent(<span class="keyword">Description</span>.<span class="keyword">class</span>);</span><br><span class="line">				<span class="keyword">if</span>(isHave)&#123;</span><br><span class="line">					<span class="keyword">Description</span> d = (<span class="keyword">Description</span>)m.getAnnotation(<span class="keyword">Description</span>.<span class="keyword">class</span>);</span><br><span class="line">					System.out.<span class="keyword">println</span>(d.desc());</span><br><span class="line">				&#125;</span><br><span class="line">			&#125;</span><br><span class="line">			</span><br><span class="line">			<span class="comment">//5. 另外一种方法上的注解的方式</span></span><br><span class="line">			<span class="keyword">for</span>(Method m: methods)&#123;</span><br><span class="line">				Annotation[] annotations = m.getAnnotations();</span><br><span class="line">				<span class="keyword">for</span>(Annotation a: annotations)&#123;</span><br><span class="line">					<span class="keyword">if</span>(a <span class="keyword">instanceof</span> <span class="keyword">Description</span>)&#123;</span><br><span class="line">						<span class="keyword">Description</span> d = (<span class="keyword">Description</span>)a;</span><br><span class="line">						System.out.<span class="keyword">println</span>(d.desc());</span><br><span class="line">					&#125;</span><br><span class="line">				&#125;</span><br><span class="line">			&#125;</span><br><span class="line">		&#125; <span class="keyword">catch</span> (ClassNotFoundException e) &#123;</span><br><span class="line">			<span class="comment">// TODO Auto-generated catch block</span></span><br><span class="line">			e.printStackTrace();</span><br><span class="line">		&#125;</span><br><span class="line">	&#125;</span><br><span class="line">&#125;</span><br></pre></td></tr></table></figure>

<h2 id="应用实战"><a href="#应用实战" class="headerlink" title="应用实战"></a>应用实战</h2><ol>
<li>项目目标： 通过注解实现sql代码</li>
<li>项目需求：<br><img src="/blog/images/20191111154105111.jpg" alt="项目需求"></li>
</ol>
<h3 id="开发过程"><a href="#开发过程" class="headerlink" title="开发过程"></a>开发过程</h3><ol>
<li><p>创建实体类</p>
<figure class="highlight kotlin"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br><span class="line">7</span><br><span class="line">8</span><br><span class="line">9</span><br><span class="line">10</span><br><span class="line">11</span><br><span class="line">12</span><br><span class="line">13</span><br><span class="line">14</span><br><span class="line">15</span><br><span class="line">16</span><br><span class="line">17</span><br><span class="line">18</span><br><span class="line">19</span><br></pre></td><td class="code"><pre><span class="line"><span class="comment">//实体类 </span></span><br><span class="line"><span class="meta">@Table(<span class="meta-string">"user_entity"</span>)</span></span><br><span class="line"><span class="keyword">public</span> <span class="class"><span class="keyword">class</span> <span class="title">UserEntity</span> </span>&#123;</span><br><span class="line">	<span class="meta">@Column(<span class="meta-string">"id"</span>)</span></span><br><span class="line">	<span class="keyword">private</span> int id;</span><br><span class="line">	<span class="meta">@Column(<span class="meta-string">"user_name"</span>)</span></span><br><span class="line">	<span class="keyword">private</span> String userName;</span><br><span class="line">	<span class="meta">@Column(<span class="meta-string">"nick_name"</span>)</span></span><br><span class="line">	<span class="keyword">private</span> String nickName;</span><br><span class="line">	<span class="meta">@Column(<span class="meta-string">"age"</span>)</span></span><br><span class="line">	<span class="keyword">private</span> int age;</span><br><span class="line">	<span class="meta">@Column(<span class="meta-string">"city"</span>)</span></span><br><span class="line">	<span class="keyword">private</span> String city;</span><br><span class="line">	<span class="meta">@Column(<span class="meta-string">"email"</span>)</span></span><br><span class="line">	<span class="keyword">private</span> String email;</span><br><span class="line">	<span class="meta">@Column(<span class="meta-string">"mobile"</span>)</span></span><br><span class="line">	<span class="keyword">private</span> String mobile;</span><br><span class="line">	<span class="comment">//getter、setter</span></span><br><span class="line">&#125;</span><br></pre></td></tr></table></figure>
</li>
<li><p>创建关联实体类与数据库表的注解</p>
<figure class="highlight less"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br><span class="line">7</span><br><span class="line">8</span><br><span class="line">9</span><br><span class="line">10</span><br><span class="line">11</span><br><span class="line">12</span><br><span class="line">13</span><br><span class="line">14</span><br><span class="line">15</span><br></pre></td><td class="code"><pre><span class="line"><span class="variable">@Target</span>(&#123;ElementType.TYPE&#125;)</span><br><span class="line"><span class="variable">@Retention</span>(RetentionPolicy.RUNTIME)</span><br><span class="line"><span class="variable">@Inherited</span></span><br><span class="line"><span class="variable">@Documented</span></span><br><span class="line">public <span class="variable">@interface</span> Table &#123;</span><br><span class="line">	<span class="selector-tag">String</span> <span class="selector-tag">value</span>();</span><br><span class="line">&#125;</span><br><span class="line"></span><br><span class="line">@<span class="selector-tag">Target</span>(&#123;<span class="selector-tag">ElementType</span><span class="selector-class">.FIELD</span>&#125;)</span><br><span class="line">@<span class="selector-tag">Retention</span>(RetentionPolicy.RUNTIME)</span><br><span class="line">@<span class="selector-tag">Inherited</span></span><br><span class="line">@<span class="selector-tag">Documented</span></span><br><span class="line"><span class="selector-tag">public</span> @<span class="selector-tag">interface</span> <span class="selector-tag">Column</span> &#123;</span><br><span class="line">	<span class="selector-tag">String</span> <span class="selector-tag">value</span>();</span><br><span class="line">&#125;</span><br></pre></td></tr></table></figure>
</li>
<li><p>通过注解实现sql代码</p>
<figure class="highlight processing"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br><span class="line">7</span><br><span class="line">8</span><br><span class="line">9</span><br><span class="line">10</span><br><span class="line">11</span><br><span class="line">12</span><br><span class="line">13</span><br><span class="line">14</span><br><span class="line">15</span><br><span class="line">16</span><br><span class="line">17</span><br><span class="line">18</span><br><span class="line">19</span><br><span class="line">20</span><br><span class="line">21</span><br><span class="line">22</span><br><span class="line">23</span><br><span class="line">24</span><br><span class="line">25</span><br><span class="line">26</span><br><span class="line">27</span><br><span class="line">28</span><br><span class="line">29</span><br><span class="line">30</span><br><span class="line">31</span><br><span class="line">32</span><br><span class="line">33</span><br><span class="line">34</span><br><span class="line">35</span><br><span class="line">36</span><br><span class="line">37</span><br><span class="line">38</span><br><span class="line">39</span><br><span class="line">40</span><br><span class="line">41</span><br><span class="line">42</span><br><span class="line">43</span><br><span class="line">44</span><br><span class="line">45</span><br><span class="line">46</span><br><span class="line">47</span><br><span class="line">48</span><br><span class="line">49</span><br><span class="line">50</span><br><span class="line">51</span><br><span class="line">52</span><br><span class="line">53</span><br><span class="line">54</span><br><span class="line">55</span><br><span class="line">56</span><br><span class="line">57</span><br><span class="line">58</span><br><span class="line">59</span><br><span class="line">60</span><br><span class="line">61</span><br><span class="line">62</span><br><span class="line">63</span><br><span class="line">64</span><br><span class="line">65</span><br><span class="line">66</span><br><span class="line">67</span><br><span class="line">68</span><br><span class="line">69</span><br><span class="line">70</span><br><span class="line">71</span><br><span class="line">72</span><br><span class="line">73</span><br><span class="line">74</span><br><span class="line">75</span><br></pre></td><td class="code"><pre><span class="line"><span class="keyword">public</span> class Test &#123;</span><br><span class="line">	<span class="keyword">public</span> <span class="keyword">static</span> <span class="keyword">void</span> main(<span class="keyword">String</span>[] args) &#123;</span><br><span class="line">		UserEntity u1 = <span class="keyword">new</span> UserEntity();</span><br><span class="line">		u1.setId(<span class="number">10</span>); <span class="comment">//精确查询id=10的用户</span></span><br><span class="line">		</span><br><span class="line">		UserEntity u2 = <span class="keyword">new</span> UserEntity();</span><br><span class="line">		u2.setUserName(<span class="string">"lucy"</span>); <span class="comment">//模糊查询用户名为lucy的用户</span></span><br><span class="line">		</span><br><span class="line">		UserEntity u3 = <span class="keyword">new</span> UserEntity();</span><br><span class="line">		u3.setEmail(<span class="string">"liu@sin.com, zh@163.com"</span>);<span class="comment">//查询邮箱为其中任意一个的用户</span></span><br><span class="line">		</span><br><span class="line">		<span class="comment">//打印SQL语句</span></span><br><span class="line">		System.out.<span class="built_in">println</span>(query(u1));</span><br><span class="line">		System.out.<span class="built_in">println</span>(query(u2));</span><br><span class="line">		System.out.<span class="built_in">println</span>(query(u3));</span><br><span class="line">	&#125;</span><br><span class="line">	</span><br><span class="line">	<span class="keyword">private</span> <span class="keyword">static</span> <span class="keyword">String</span>  query(UserEntity userEntity) &#123;</span><br><span class="line">		StringBuilder sbBuilder  = <span class="keyword">new</span> StringBuilder();</span><br><span class="line">		<span class="comment">//1. 获取CLass</span></span><br><span class="line">		Class class1 = userEntity.getClass();</span><br><span class="line">		<span class="comment">//2. 判断@table注解是否存在</span></span><br><span class="line">		<span class="built_in">boolean</span> exists = class1.isAnnotationPresent(<span class="keyword">Table</span>.class);</span><br><span class="line">		<span class="keyword">if</span>(!exists) <span class="keyword">return</span> <span class="keyword">null</span>;</span><br><span class="line">		<span class="comment">//3. 通过@table注解来获取类上标注的数据库表的名称</span></span><br><span class="line">		<span class="keyword">Table</span> table = (<span class="keyword">Table</span>) class1.getAnnotation(<span class="keyword">Table</span>.class);</span><br><span class="line">		<span class="keyword">String</span> tableName = table.value();</span><br><span class="line">		<span class="comment">//4. 拼接sql</span></span><br><span class="line">		sbBuilder.<span class="built_in">append</span>(<span class="string">"select * from "</span>).<span class="built_in">append</span>(tableName).<span class="built_in">append</span>(<span class="string">" where 1=1 "</span>);</span><br><span class="line">		<span class="comment">//5. 遍历类中的所有字段，处理每个字段对应的sql</span></span><br><span class="line">		Field[] fArray = class1.getDeclaredFields();</span><br><span class="line">		<span class="keyword">for</span>(Field f: fArray)&#123;</span><br><span class="line">			<span class="comment">//5.1 处理加了@Column注解的字段</span></span><br><span class="line">			<span class="keyword">if</span>(!f.isAnnotationPresent(Column.class))&#123;</span><br><span class="line">				<span class="keyword">continue</span>;</span><br><span class="line">			&#125;</span><br><span class="line">			<span class="comment">//5.2 获取字段的名称和值</span></span><br><span class="line">			Column column  = f.getAnnotation(Column.class);</span><br><span class="line">			<span class="keyword">String</span> columnName = column.value();</span><br><span class="line">			<span class="keyword">String</span> fieldName = f.getName();</span><br><span class="line">			<span class="keyword">Object</span> filedValue = <span class="string">""</span>;</span><br><span class="line">			<span class="keyword">String</span> getMethodName = <span class="string">"get"</span>+fieldName.substring(<span class="number">0</span>,<span class="number">1</span>).toUpperCase() + fieldName.substring(<span class="number">1</span>);</span><br><span class="line">			<span class="keyword">try</span> &#123;</span><br><span class="line">				Method method = class1.getMethod(getMethodName);</span><br><span class="line">				filedValue = (<span class="keyword">Object</span>)method.invoke(userEntity);</span><br><span class="line">			&#125; <span class="keyword">catch</span> (Exception e) &#123;</span><br><span class="line">				e.printStackTrace();</span><br><span class="line">			&#125; </span><br><span class="line">			</span><br><span class="line">			<span class="comment">//6.3 拼接sql</span></span><br><span class="line">			<span class="keyword">if</span>(filedValue == <span class="keyword">null</span> || (filedValue <span class="keyword">instanceof</span> Integer &amp;&amp; (Integer)filedValue == <span class="number">0</span>))&#123;</span><br><span class="line">				<span class="keyword">continue</span>;</span><br><span class="line">			&#125;</span><br><span class="line">			</span><br><span class="line">			<span class="keyword">if</span>(filedValue <span class="keyword">instanceof</span> Integer)&#123;</span><br><span class="line">				sbBuilder.<span class="built_in">append</span>(<span class="string">" and "</span>).<span class="built_in">append</span>(fieldName).<span class="built_in">append</span>(<span class="string">"="</span>).<span class="built_in">append</span>(filedValue);</span><br><span class="line">			&#125;<span class="keyword">else</span> <span class="keyword">if</span>(filedValue <span class="keyword">instanceof</span> <span class="keyword">String</span>)&#123;</span><br><span class="line">				<span class="comment">//System.out.println(((String) filedValue).contains(","));</span></span><br><span class="line">				<span class="keyword">if</span>(((<span class="keyword">String</span>) filedValue).contains(<span class="string">","</span>))&#123;</span><br><span class="line">					<span class="keyword">String</span>[] value = ((<span class="keyword">String</span>) filedValue).<span class="built_in">split</span>(<span class="string">","</span>);</span><br><span class="line">					sbBuilder.<span class="built_in">append</span>(<span class="string">" and "</span>).<span class="built_in">append</span>(fieldName).<span class="built_in">append</span>(<span class="string">" in ("</span>);</span><br><span class="line">					<span class="keyword">for</span>(<span class="keyword">String</span> v: value)&#123;</span><br><span class="line">						sbBuilder.<span class="built_in">append</span>(<span class="string">"'"</span>).<span class="built_in">append</span>(v).<span class="built_in">append</span>(<span class="string">"',"</span>);</span><br><span class="line">					&#125;</span><br><span class="line">					sbBuilder.deleteCharAt(sbBuilder.length()<span class="number">-1</span>);</span><br><span class="line">					sbBuilder.<span class="built_in">append</span>(<span class="string">")"</span>);</span><br><span class="line">				&#125;<span class="keyword">else</span>&#123;</span><br><span class="line">					sbBuilder.<span class="built_in">append</span>(<span class="string">" and "</span>).<span class="built_in">append</span>(fieldName).<span class="built_in">append</span>(<span class="string">" like"</span>).<span class="built_in">append</span>(<span class="string">"'%"</span>).<span class="built_in">append</span>(filedValue).<span class="built_in">append</span>(<span class="string">"%'"</span>);</span><br><span class="line">				&#125;</span><br><span class="line">			&#125;</span><br><span class="line">			</span><br><span class="line">		&#125;</span><br><span class="line">		<span class="keyword">return</span> sbBuilder.toString();</span><br><span class="line">	&#125;</span><br><span class="line">&#125;</span><br></pre></td></tr></table></figure>
</li>
<li><p>将query方法通用化<br><img src="/blog/images/20191111165346651.jpg" alt="将query方法通用化"></p>
</li>
</ol>
<h2 id="注解总结"><a href="#注解总结" class="headerlink" title="注解总结"></a>注解总结</h2><ol>
<li><p>中级：认识注解：</p>
<blockquote>
<p>注解的作用范围@Target: 包、类、字段、方法、方法的参数、局部变量<br>注解的生命周期@Retention：源文件SOURCE、编译CLASS、运行RUNTIME</p>
</blockquote>
</li>
<li><p>高级：读懂注解</p>
</li>
<li><p>最高级：能再实际项目中通过注解解决问题，并能自定义注解</p>
</li>
</ol>

      
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              <div class="post-toc-content"><ol class="nav"><li class="nav-item nav-level-2"><a class="nav-link" href="#Java注解"><span class="nav-number">1.</span> <span class="nav-text">Java注解</span></a></li><li class="nav-item nav-level-2"><a class="nav-link" href="#注解分类"><span class="nav-number">2.</span> <span class="nav-text">注解分类</span></a></li><li class="nav-item nav-level-2"><a class="nav-link" href="#自定义注解"><span class="nav-number">3.</span> <span class="nav-text">自定义注解</span></a><ol class="nav-child"><li class="nav-item nav-level-3"><a class="nav-link" href="#创建自定义注解"><span class="nav-number">3.1.</span> <span class="nav-text">创建自定义注解</span></a></li><li class="nav-item nav-level-3"><a class="nav-link" href="#使用自定义注解"><span class="nav-number">3.2.</span> <span class="nav-text">使用自定义注解</span></a></li><li class="nav-item nav-level-3"><a class="nav-link" href="#解析注解"><span class="nav-number">3.3.</span> <span class="nav-text">解析注解</span></a></li></ol></li><li class="nav-item nav-level-2"><a class="nav-link" href="#应用实战"><span class="nav-number">4.</span> <span class="nav-text">应用实战</span></a><ol class="nav-child"><li class="nav-item nav-level-3"><a class="nav-link" href="#开发过程"><span class="nav-number">4.1.</span> <span class="nav-text">开发过程</span></a></li></ol></li><li class="nav-item nav-level-2"><a class="nav-link" href="#注解总结"><span class="nav-number">5.</span> <span class="nav-text">注解总结</span></a></li></ol></div>
            

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                      start: start,
                      end: end,
                      searchTextCount: searchTextCountInSlice
                    };
                  }

                  var slicesOfTitle = [];
                  if (indexOfTitle.length != 0) {
                    slicesOfTitle.push(mergeIntoSlice(title, 0, title.length, indexOfTitle));
                  }

                  var slicesOfContent = [];
                  while (indexOfContent.length != 0) {
                    var item = indexOfContent[indexOfContent.length - 1];
                    var position = item.position;
                    var word = item.word;
                    // cut out 100 characters
                    var start = position - 20;
                    var end = position + 80;
                    if(start < 0){
                      start = 0;
                    }
                    if (end < position + word.length) {
                      end = position + word.length;
                    }
                    if(end > content.length){
                      end = content.length;
                    }
                    slicesOfContent.push(mergeIntoSlice(content, start, end, indexOfContent));
                  }

                  // sort slices in content by search text's count and hits' count

                  slicesOfContent.sort(function (sliceLeft, sliceRight) {
                    if (sliceLeft.searchTextCount !== sliceRight.searchTextCount) {
                      return sliceRight.searchTextCount - sliceLeft.searchTextCount;
                    } else if (sliceLeft.hits.length !== sliceRight.hits.length) {
                      return sliceRight.hits.length - sliceLeft.hits.length;
                    } else {
                      return sliceLeft.start - sliceRight.start;
                    }
                  });

                  // select top N slices in content

                  var upperBound = parseInt('1');
                  if (upperBound >= 0) {
                    slicesOfContent = slicesOfContent.slice(0, upperBound);
                  }

                  // highlight title and content

                  function highlightKeyword(text, slice) {
                    var result = '';
                    var prevEnd = slice.start;
                    slice.hits.forEach(function (hit) {
                      result += text.substring(prevEnd, hit.position);
                      var end = hit.position + hit.length;
                      result += '<b class="search-keyword">' + text.substring(hit.position, end) + '</b>';
                      prevEnd = end;
                    });
                    result += text.substring(prevEnd, slice.end);
                    return result;
                  }

                  var resultItem = '';

                  if (slicesOfTitle.length != 0) {
                    resultItem += "<li><a href='" + articleUrl + "' class='search-result-title'>" + highlightKeyword(title, slicesOfTitle[0]) + "</a>";
                  } else {
                    resultItem += "<li><a href='" + articleUrl + "' class='search-result-title'>" + title + "</a>";
                  }

                  slicesOfContent.forEach(function (slice) {
                    resultItem += "<a href='" + articleUrl + "'>" +
                      "<p class=\"search-result\">" + highlightKeyword(content, slice) +
                      "...</p>" + "</a>";
                  });

                  resultItem += "</li>";
                  resultItems.push({
                    item: resultItem,
                    searchTextCount: searchTextCount,
                    hitCount: hitCount,
                    id: resultItems.length
                  });
                }
              })
            };
            if (keywords.length === 1 && keywords[0] === "") {
              resultContent.innerHTML = '<div id="no-result"><i class="fa fa-search fa-5x" /></div>'
            } else if (resultItems.length === 0) {
              resultContent.innerHTML = '<div id="no-result"><i class="fa fa-frown-o fa-5x" /></div>'
            } else {
              resultItems.sort(function (resultLeft, resultRight) {
                if (resultLeft.searchTextCount !== resultRight.searchTextCount) {
                  return resultRight.searchTextCount - resultLeft.searchTextCount;
                } else if (resultLeft.hitCount !== resultRight.hitCount) {
                  return resultRight.hitCount - resultLeft.hitCount;
                } else {
                  return resultRight.id - resultLeft.id;
                }
              });
              var searchResultList = '<ul class=\"search-result-list\">';
              resultItems.forEach(function (result) {
                searchResultList += result.item;
              })
              searchResultList += "</ul>";
              resultContent.innerHTML = searchResultList;
            }
          }

          if ('auto' === 'auto') {
            input.addEventListener('input', inputEventFunction);
          } else {
            $('.search-icon').click(inputEventFunction);
            input.addEventListener('keypress', function (event) {
              if (event.keyCode === 13) {
                inputEventFunction();
              }
            });
          }

          // remove loading animation
          $(".local-search-pop-overlay").remove();
          $('body').css('overflow', '');

          proceedsearch();
        }
      });
    }

    // handle and trigger popup window;
    $('.popup-trigger').click(function(e) {
      e.stopPropagation();
      if (isfetched === false) {
        searchFunc(path, 'local-search-input', 'local-search-result');
      } else {
        proceedsearch();
      };
    });

    $('.popup-btn-close').click(onPopupClose);
    $('.popup').click(function(e){
      e.stopPropagation();
    });
    $(document).on('keyup', function (event) {
      var shouldDismissSearchPopup = event.which === 27 &&
        $('.search-popup').is(':visible');
      if (shouldDismissSearchPopup) {
        onPopupClose();
      }
    });
  </script>





  

  

  

  
  

  

  

  

</body>
</html>
